Distance measurement 3

Changes to Distance Calculation
1. Move DistanceCalculationLayer to reside above ContextMenuLayer and increase independence.
2. Modify UI for greater consistency and to provide independent point editing menu.
3. Provide feedback for point dragging
4. Change subtrack strategy: subtracks are always connected.
5. Add subtrack identification coloring and separate distance measurements for subtrack, cumulative distanace to selected point and total distance.
6. Add capability to add note to any point and display.
7. Add ability to display lat and lon for selected points
8. Add point insertion capability